Exhaust bolt question

I was riding my 80 XJ650 home the other day and all of a sudden it sounded a whole lot louder. Then I lost power. I discovered that on my #3 cylinder one of the previous owners had evidently snapped the stud for the exhaust off and decided a piece of bailing wire through a hole drilled in one of the air fins on the head to the exhaust flange would be the best solution. I'm fine with that, but the problem is that the nut came off the other stud on that flange. I was able to crank up the choke to make it run a little richer to compensate for the bad back pressure and get it home, but I'm not gonna continue to ride it like that. Does anyone know the nut size so I can go down to Lowes and pick one up? I dont want to pull one of the others off and chance breaking it too. I just need a band-aid fix for now until I bring the bike in the garage this winter to do a bunch of work that I'm planning on.

 

Probably won't find one at Lowes, Yamaha uses odd metric PITCH threads that aren't commonly available.

If nobody else gives you an answer, I can look it up when I get home.

 

M 6X1 per Polock on this thread: http://www.xjbikes.com/Forums/viewtopic ... rt=15.html

 

thanks for the help, I tried to look around and find a post on it already but couldnt find one. I'll hit the specialty fastener store on the way home today.

 

I picked up a pack of nuts for it on my way home the other day, and got it put back together. Then I realized I had a couple left over so I decided to put a jam nut on too. BAD IDEA! i wasnt really pulling that hard on it, and busted off another stud. So no my #3 cylinder has no exhaust studs, I picked up some left hand drill bits, but ended up off center and elongated my hole and still didnt get the old bolt out. How deep do I need to be to fit a helicoil in the hole? I just wanna get it back on the road for the rest of the summer.

 

some helicoil's take special size drills and i think they all take special taps and come in several lengths
the hole you started most likely is going to get more elongated the deeper you go
be careful or your taking the head to a machine shop

 

Yep I've been down that road before.
Because both are broken you probably need to bite the bullet and take the head to a machine shop.

If I was doing it I would look for another head... aluminum + 2 brittle broken studs = big $$$.00.

Good luck
ab

 

I had 4 broken studs when I first rebuilt my engine and a old school machinist drilled and helicoiled it for $45 bucks. He admitted he underquoted me and took almost 3 weeks to get it back to me due to it not being a priority due to that. If you get the head off and bring it in I don't see it costing you more than $50 bucks.

 

lol they sure are easy to snap off... i recently snapped one while redoing my entire exhaust system

i was able to drill the stuck stud out enough to get a replacement stud in

chacal has the OEM looking studs and nuts and all that but, yea, Lowe's has some M6 x 1 nuts and studs... i just had to chop the Lowe's stud to get it the right length

the Lowe's nuts kinda make it look cheesy but only if you look really closely

 

Does anyone have an idea what a used head should run me? I know there is a bike salvage/shop here in town that has one, I havent asked him the price on it yet though. I just want to make sure I'm not bending over for the guy when he tells me.

 

You can get one on ebay for $30 bucks, but shipping is a little steep. There isn't much of a market for them.

 

They are not in perfect shape but I have a set of four. PM me an offer. I don't have the studs or nuts however.

 

Ok, So i tried and tried to drill. ended up with an elongated hole. Couldn't get a heli-coil in it. My final solution came to me while I was in bed last night. It worked as temporary solution until this winter when i pull the bike down and can get a better shot at it. I ended up wrapping a hose clamp around the frame and exhaust pipe to make it hold. I got a sheet of make your own gasket stuff from Auto Zone and put a double layer in the port, and next thing you know, I'm putting down the road. It doesnt look that pretty, but if you saw the rest of the bike, you would understand my lack of concern about the way this looks.

 

Since, ... by your own admission you don't care about pretty; here's a Jury-Rig that will help you through the storm.

Oil a Stud.
Shake-off the Oil and WRAP it with 3 Layers of Teflon Tape.
Tight. You want the threads covered good.
Coat the Teflon with a good-bit of JB Weld.

Stick the JB Weld-on-it Stud in the Hole.
Trowel JB Weld in any air gap. Fill the space.
Before the JB Weld gets too hard to mess with ... scrape, cut and pimp.

When the JB Weld hardens-up.
Run a nut on the stud.
Place a washer on the stud.
Another nut ...

Tighten the Nuts against each-other.
Wrench the INSIDE Nut OUT.

If you did it right, ... the Oily Teflon Tape lets the STUD Unscrew and leaves threads to use for a Bolt or another Stud.

 

I was thinking about something like that with some of that drillable 2 part epoxy putty. I've actually used it to fix broken exhaust studs on diesel engines as well. Right now I'm just trying to get through the last few weeks of the best riding weather in Oklahoma. We'll see what this winter brings along as far as breaking it down. Thanks for the advice.

 

If you want too, ... all you really need to do is drill it out to the next oversize.

Metric or SAE.
Tap the Hole.
Enlarge the Hole on the Collar.

Use a Hardened Cap Screw to be the NEW Fastener.
((As you get them out, ... if they DO come out ... it ain't a bad idea to replace every garbage Stud and Fastener YAMAHA used to build the Bike.))